README.md

About this demo

This app demo has a propose to demonstrate how to implement the oauth authentication in Android apps.

IMPORTANT:

Chrome Custom Tabs has no method to close itself, and this implementation is based on redirecting to previous Activity, by Intent flags, finishing the called Activity with registered scheme.

Introduction

These are some example how to implement a sign-in on OAuth flow to use Trustly JavaScript SDK. The code is using Kotlin language implementation.

WebClient

There are two ways to create web clients for a WebView, WebViewClient and WebChromeClient.

WebViewClient implementation

Using WebViewClient you'll need to add a configuration in the settings property. Set the javaScriptCanOpenWindowsAutomatically property to true in order to enable the application to properly handle window.open events.

    webView.settings.apply {
        javaScriptCanOpenWindowsAutomatically = true
    }

Using WebViewClient you can override many methods, but you need to implement the shouldOverrideUrlLoading method. This method determines what will happen when a URL is loaded in WebView. The example below is a simple implementation that calls the method which opens the CustomTabs.

    webView.webViewClient = object : WebViewClient() {
        override fun shouldOverrideUrlLoading(view: WebView, request: WebResourceRequest): Boolean {
            val url = request.url.toString()
            if (url.contains(TrustlyConstants.OAUTH_LOGIN_PATH))
                launchUrl(this@WebViewClientActivity, url)
            return true
        }
    }

WebChromeClient implementation

Using WebChromeClient you'll need to create your own WebView, add some configuration in the settings property, and transport itself to a custom WebView. The example below explain more about those implementation. First you need to add both javaScriptCanOpenWindowsAutomatically and setSupportMultipleWindows(true), they are needed to listen the window.open method.

    webView.settings.apply {
        javaScriptCanOpenWindowsAutomatically = true
        setSupportMultipleWindows(true)
    }

This is the WebChromeClient implementation, using a custom WebView to transport the URL and than open it inside that. The trustlyWebView is an instance of the custom WebView, which has the same implementation of a WebViewClient.

    webView.webChromeClient = object : WebChromeClient() {
        override fun onCreateWindow(view: WebView, isDialog: Boolean, isUserGesture: Boolean, resultMsg: Message): Boolean {
            return if (view.hitTestResult.type == 0) {
                //window.open
                webView.addView(trustlyWebView)
                val transport = resultMsg.obj as WebViewTransport
                transport.webView = trustlyWebView.webView
                resultMsg.sendToTarget()
                true
            } else false
        }
    }

CustomTabsIntent

It is a simple custom view with a WebView inside, to open the transported url. In your custom web view you need to create a CustomTabIntent to open the url:

    private fun launchUrl(context: Context, url: String) {
        val customTabsIntent = CustomTabsIntent.Builder().build()
        customTabsIntent.launchUrl(context, Uri.parse(url))
    }

TrustlyWebChromeClientRedirectActivity and TrustlyWebViewClientRedirectActivity

When the application receive some action for example web-chrome-client-redirect, or the name that you defined in urlScheme, it will call your target Activity with some flags, and reload it. The example below is from TrustlyWebChromeClientRedirectActivity

    Intent(this, WebChromeClientActivity::class.java).apply {
        addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP)
    }.run { startActivity(this) }
    finish()

AndroidManifest

    <activity
    android:name=".TrustlyWebChromeClientRedirectActivity"
    android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.VIEW" />
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:scheme="web-chrome-client-redirect" />
        </intent-filter>
    </activity>

ProceedToChooseAccount

Finally, in order to support a smooth user experience when an OAuth login authorization is completed and the user returns to the Lightbox, call this function using some code like this:

    webView.loadUrl("javascript:window.Trustly.proceedToChooseAccount();")